220530991 has 4 divisors (see below), whose sum is σ = 220894912. Its totient is φ = 220167072.

The previous prime is 220530983. The next prime is 220530997. The reversal of 220530991 is 199035022.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199035022 = 2 ⋅99517511.

It is a cyclic number.

It is not a de Polignac number, because 220530991 - 2³ = 220530983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (220530997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 181050 + ... + 182263.

It is an arithmetic number, because the mean of its divisors is an integer number (55223728).

Almost surely, 2^220530991 is an apocalyptic number.

220530991 is a deficient number, since it is larger than the sum of its proper divisors (363921).

220530991 is an equidigital number, since it uses as much as digits as its factorization.

220530991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363920.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 220530991 is about 14850.2858895039. The cubic root of 220530991 is about 604.1663640892.

The spelling of 220530991 in words is "two hundred twenty million, five hundred thirty thousand, nine hundred ninety-one".